Respiratory-based control of medical procedure

ABSTRACT

A medical system ( 100 ) is disclosed that provides a respiratory-based control of at least one medical procedure. In this regard, the medical system ( 100 ) includes one or more appropriate sensors ( 108 ) for providing respiratory data on a patient ( 104 ). This respiratory data is utilized by respiration assessment logic ( 116 ) to determine if the respiratory data has exceeded one or more respiration thresholds and which may be equated with a “sudden” respiratory event. Identification of such a sudden respiratory event by the logic ( 116 ) results in the suspension of the noted medical procedure. Patient respiration data may also be displayed, for instance in a color that depends upon its magnitude or level.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/924,989, filed 26 Oct. 2007 (the '989 application), now ______, whichin turn claims the benefit of and priority to U.S. application No.60/894,045, filed 9 Mar. 2007 (the '045 application). The '989application and '045 application are each hereby incorporated byreference as though fully set forth herein.

BACKGROUND OF THE INVENTION

a. Field of the Invention

The instant invention is directed toward suspending, modifying, orcontrolling a medical procedure under certain conditions. Morespecifically, the instant invention relates to monitoring patientrespiratory data and suspending, modifying, or controlling a medicalprocedure upon encountering an exceedance of at least one respiratorythreshold.

b. Background

Cardiac mapping systems such as the Ensite™ Advanced Mapping System bySt. Jude Medical, Inc., and the Carto™ Electroanatomical Mapping Systemby Biosense Webster provide non-fluoroscopic navigation of conventionalelectrophysiology catheters. The Ensite™ Advanced Mapping System'snavigation methodology is based on the principle that when electricalcurrent is applied across two surface electrodes, a voltage gradient iscreated along the axis between the electrodes. While any number ofelectrode pairs may be used, typically, six surface electrodes areplaced on the body of the patient in three pairs: anterior to posterior,left to right lateral, and superior (neck) to inferior (left leg). Thethree electrode pairs form three orthogonal axes (X-Y-Z), with thepatient's heart being at least generally at the center.

The noted surface electrode pairs are connected to the Ensite™ AdvancedMapping System, which alternately sends an electrical signal througheach pair of surface electrodes to create a voltage gradient along eachaxis, forming a transthoracic electrical field. Conventionalelectrophysiology catheters may be connected to the Ensite™ AdvancedMapping System and advanced to the patient's heart. As a catheter entersthe transthoracic field, each catheter electrode senses voltage, timedto the creation of the gradient along each axis. Using the sensedvoltages compared to the voltage gradient on all three axes, EnSite™NavX™ navigation and visualization technology calculates thethree-dimensional position of each catheter electrode. The calculatedposition for the various electrodes occurs simultaneously and repeatsmany times per second (e.g., about 93 times per second).

The Ensite™ Advanced Mapping System displays the located electrodes ascatheter bodies with real-time navigation. By tracking the position ofthe various catheters, EnSite™ NavX™ navigation and visualizationtechnology provides non-fluoroscopic navigation, mapping, and creationof chamber models that are highly detailed and that have very accurategeometries. In the latter regard, the physician sweeps an appropriatecatheter electrode across the heart chamber to outline the structures byrelaying the signals to the computer system that then generates the 3-Dmodel. This 3-D model may be utilized for any appropriate purpose, forinstance to help the physician guide an ablation catheter to a heartlocation where treatment is desired/required.

In accordance with the foregoing, conventional electrophysiologycatheter electrodes may be located in EnSite™ NavX™ navigation andvisualization technology using a transthoracic impedance of a low-levelsignature frequency, which is sent and received between surfaceelectrodes on the patient's skin. The calculated catheter electrodepositions may be displayed relative to surface electrodes. Thesecatheter electrodes may be used to mark discrete locations within theheart, such as for building models of cardiac chambers, marking discretesites of diagnosis (mapping), or guiding and marking positions oftherapy delivery.

It should be appreciated that during respiration portions of thethoracic cavity move relative to the surface electrodes and volumes maychange. Thus, catheter electrodes in the heart move relative to thesurface electrodes. Current systems do not account for this movement,and are accordingly creating static labeling of a dynamic model. Thiscan cause errors in location, map generation and display, and treatment.

Current systems can try to correct for this artifactual motion by arespiration compensation functionality that is incorporated into theEnsite™ Advanced Mapping System. A respiration compensationfunctionality is utilized in the Ensite™ Advanced Mapping System toadjust to respiratory motion from intracardiac catheters by: (1) takinga 12-second data sample of patient respiration, including motion onintracardiac electrodes and impedance changes measured by the EnSite™NavX™ navigation and visualization technology surface electrodes; and(2) following the collection of such a respiration data sample, therespiration compensation functionality may monitor the surface electrodeimpedance, and as the impedance changes, the respiration compensationfunctionality will adaptively compensate for motion artifacts onintracardiac electrode navigation. However, the respiration compensationfunctionality will only adapt to respiration levels (impedance levels)within the range measured during the sample. Respiration can also causesimilar difficulties in systems that do no use surface electrodes.

BRIEF SUMMARY OF THE INVENTION

A first aspect of the present invention is embodied by a medical systemthat includes at least one sensor (e.g., a first sensor) and what may becharacterized as respiration assessment logic. The first sensor may bepositioned relative to a patient such that its output provides patient'srespiration data. The respiration assessment logic may be operativelyinterconnected with the first sensor and is configured to identify theexistence of a first condition. Although not required by the firstaspect, any action or combination of actions may be initiated inresponse to the identification of a first condition. For instance, atleast a first medical procedure may be suspended if the respirationassessment logic identifies an occurrence of the first condition.Another option would be to provide an appropriate notification as to theexistence of the first condition if the respiration assessment logicidentifies an occurrence of a first condition.

A second aspect of the present invention is embodied by a method forperforming a first medical procedure. Patient respiration data isacquired during the execution of the first medical procedure. Thispatient respiration data may be evaluated in any appropriate manner. Ifthis evaluation identifies the existence of a first condition, furtherexecution of the first medical procedure is suspended, modified, orcontrolled based on respiration data for at least a certain period oftime.

A third aspect of the present invention is embodied by a method forperforming a first medical procedure. A first patient respiration datasample is acquired, and that includes at least one complete patientrespiration cycle. The first medical procedure may include marking aplurality of physiological locations. Patient respiration data isacquired during the first medical procedure. This patient respirationdata may be evaluated in any appropriate manner, but in any caseutilizing the first patient respiration data sample in at least somerespect. If this evaluation identifies the existence of a firstcondition, marking procedures are suspended for at least a certainperiod of time.

A fourth aspect of the present invention is embodied by a system/methodthat may be used to control a first medical procedure, although controlmay not be required in all instances. Patient respiration data isacquired. This patient respiration data may be evaluated in anyappropriate manner. The patient's respiration level is displayed in acolor that depends upon the magnitude of the respiration level.Respiration levels within a first range of any appropriate size aredisplayed in a first color, while respiration levels within a secondrange of any appropriate size are displayed in a second color that isdifferent than the first color.

Various refinements and/or additional features that may be utilized inrelation to each of the above-noted aspects will now be addressed, andwhich may be used individually or in any combination. The variousfeatures addressed above in relation to each particular aspect also maybe utilized in any of the other aspects, individually or in anycombination.

The patient respiration data may be in any form, but is preferablyreflective of the patient's respiration level. In any case, the firstcondition may be one that has at least some type of adverse effect on orin relation to the first medical procedure, and which may be identifiedthrough assessment of patient respiration data. The first condition maybe equated with what may be characterized as a sudden respiratory event.Representative sudden respiratory events include without limitationgasping, sighing, talking, coughing, or snoring.

A number of characterizations may be made in relation to the firstcondition. One such characterization is that the first condition isrepresentative of a patient respiration that exceeds one or morerespiration thresholds. Another such characterization is that the firstcondition is representative of a patient respiration that is outside ofa predetermined respiration range (e.g., having a pair of limits orthresholds). Yet another characterization is that the first condition isrepresentative of a patient respiration that exceeds a baselinerespiration by more than a certain, predetermined amount or percentage.One respiration threshold may be associated with the end of inhalationduring normal respiration (e.g., within a certain amount of a maximuminhalation value or an average maximum inhalation value identified froman initializing patient respiration data sample), while anotherrespiration threshold may be associated with the end of exhalationduring normal respiration (e.g., within a certain amount of a maximumexhalation value or an average maximum exhalation value identified froman initializing patient respiration data sample). Any respirationthreshold or respiration range that is utilized in the assessment ofpatient respiration data may be adjusted at any appropriate time and inany appropriate manner. For instance, each respiration threshold that isutilized could be independently adjustable if desired/required and setat any appropriate level or magnitude. Multiple respiration thresholdscould also be simultaneously adjusted.

Patient respiration data may be obtained in any appropriate manner, suchas through one or more appropriate sensors (e.g., at least a “firstsensor”). Each such sensor may be of any appropriate size, shape,configuration, and/or type, and furthermore may be positioned at anyappropriate location on or otherwise relative to the patient. Forinstance, one or more sensors may be in the form of a patch electrode orthe like that is appropriately secured to the skin of the patient at anappropriate location. Multiple sensors may be utilized and disposed inany appropriate arrangement on or otherwise relative to the patient toprovide patient respiration data. In one embodiment, impedance is usedas a parameter for monitoring the patient's respiration. In this regard,the impedance between a pair of sensors may be determined in anyappropriate manner and used in the assessment of the patient respirationdata to identify any occurrence of a first condition. Any appropriateparameter or combination of parameters that would be indicative of thepatient's respiration (more specifically, the level of respiration) maybe used in the patient respiration data assessment (e.g., atransthoracic impedance; at least one electrophysiological parameter;pressure from one or more pressure-sensing catheters; one or moreoutputs from respiration equipment).

The patient respiration data assessment functionality may beincorporated/implemented in any appropriate manner, such as in software,hardware, or any combination thereof. In any case and in one embodiment,the patient respiration data assessment only evaluates an amplitude of aparameter that relates to the patient's respiration, where thisparameter corresponds with or may be derived from/using the output fromone or more sensors. For instance, although a parameter that isindicative of the patient's respiration may be conveyed in a waveform,the patient respiration data may simply determine whether any maximum orany minimum of the waveform exceeds a corresponding respirationthreshold.

Patient respiration data may be displayed in any appropriate manner andat any appropriate location (e.g., alongside a navigation display). Anygraphical/visual representation of patient respiration data may bepresented on an appropriate display. For instance, patient respirationdata may be presented on a display as a movable marker or indicator on arespiration meter with a plurality of gradations or caliper lines.Patient respiration data may be presented on this meter as a percentageof a predetermined maximum/minimum patient respiration level or value(e.g., patient respiration data may be appropriately presented on adisplay in relation to at least one predetermined respiration value).The color of this movable marker or indicator may be dependent upon itsposition on the meter to in essence provide at least two visualindicators of the patient's respiration (i.e., its physical position onthe meter, along with its color). Any appropriate number of visual orother indicators of the patient respiration data may be provided and inany appropriate manner. For instance, in addition to a color change, themovable marker or indicator, or the entire meter or at least a relevantportion thereof, may also flash when the patient respiration dataassessment has suspended the first medical procedure. The describedpatient respiration data assessment described herein may be used with orwithout respiration compensation functionality. In the former regard,the gradations of the respiration meter that correspond with respirationlevels where respiration compensation functionality is provided oravailable may be displayed in a different color than respiration levelsoutside of this respiration compensation zone.

The first condition again may be when a patient's respiration is outsideof a predetermined respiration range or above/below a certainrespiration threshold. Patient respiration data that falls within afirst portion of a predetermined respiration range may be presented in afirst color on a display (e.g., within 0% to 75% of a certainrespiration value or threshold, and which may be equated with a “normal”respiration zone), while patient respiration data that falls within asecond portion of a predetermined respiration range may be presented ina second color on a display (e.g., between 75% and 100% of a certainrespiration value or threshold, and which may be reflective of a“cautionary” respiration zone that is between the above-noted “normal”respiration zone and what may be characterized as an “unacceptable”respiration zone for purposes of the first medical procedure, where anunacceptable respiration zone may be equated with a first condition).Patient respiration data that falls outside of both the first portionand the second portion of a predetermined respiration range may bepresented in a third color on a display (e.g., patient respiration datathat is at least 100% of a certain respiration value or threshold, andwhich may be equated with a first condition). For instance, the color ofthe movable marker or indicator on the above-noted respiration meter maybe utilized for identifying the three respiration level zones or ranges.Any number of ranges or zones could be utilized, with each having itsown corresponding color.

The evaluation of the patient respiration data for purposes ofidentifying each occurrence of a first condition may benefit from aninitialization procedure. This initialization procedure may entailacquiring a patient respiration data sample, and thereafter utilizingthis patient respiration data sample in at least some fashion in thepatient respiration data evaluation. For instance, the patientrespiration data sample may be utilized to establish one or morerespiration thresholds, a respiration baseline, and/or to establish apredetermined respiration range for the patient respiration dataevaluation (e.g., to define a first condition). In one embodiment, thepatient respiration data sample includes at least one full respirationcycle that is devoid any of the above-noted types of sudden respiratoryevents (e.g., gasping, sighing, talking, coughing, snoring). It may bedesirable to repeat this initialization procedure during the performanceof the first medical procedure, for instance if the patient respirationdata is tending toward staying in the above-noted second or cautionaryrespiration zone.

The first medical procedure may be of any of appropriate type, and maybe undertaken by any appropriate component or combination of components(e.g., using one or more endocardial electrodes, such as a catheterelectrode or the like). For instance, the first medical procedure may bein the form of marking a physiological location on or within the body ofthe patient, such as a discrete location within the patient's heart. Thefirst medical procedure may also be in the form of acquiring and/orstoring anatomical/physiological location information (e.g., locationinformation of a particular anatomical structure or surface).Representative first medial procedures include without limitationcardiac labeling, cardiac geometry collection, cardiac mapping, cardiaclesion marking, and the like. The first medical procedure also may be anoperation associated with an anatomical modeling system of anyappropriate type (e.g., acquisition of anatomical/physiological locationdata, storage of anatomical/physiological location data, or both). Thatis, each of the various aspects addressed herein may be incorporatedand/or otherwise utilized by an anatomical modeling system of anyappropriate type, such as electrical-based anatomical modeling system ora magnetics-based anatomical modeling system.

The foregoing and other aspects, features, details, utilities, andadvantages of the present invention will be apparent from reading thefollowing description and claims, and from reviewing the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of one embodiment of a medicalnavigation/visualization system.

FIG. 2 is a schematic of a catheter in a heart chamber.

FIG. 3 is a representative output on a display screen used by themedical navigation/visualization system of FIG. 1, showing operation andinteraction with the overall system.

FIG. 4 is a representative output on a display screen used by themedical navigation/visualization system of FIG. 1, showing operation andinteraction with a portion of the system.

FIG. 5 is a schematic of a medical system that utilizesrespiratory-based control of a medical procedure.

FIG. 6 is a flow chart of one embodiment of a respiratory-based controlprotocol that may be utilized by the respiration assessment logic fromthe medical system of FIG. 5.

FIG. 7 is a flow chart of one embodiment of an initialization protocolthat may be utilized by the respiratory-based control protocol of FIG.6.

FIG. 8 is a flow chart of one embodiment of a respiration evaluationprotocol that may be utilized by the respiratory-based control protocolof FIG. 6.

FIG. 9 is a flow chart of another embodiment of a patient respirationevaluation protocol that may be utilized by the respiratory-basedcontrol protocol of FIG. 6.

FIG. 10A is one embodiment of a visual output that may be used by therespiratory-based control protocol of FIG. 6 to present patientrespiratory data, illustrating a patient respiration level within afirst range.

FIG. 10B is one embodiment of a visual output that may be used by therespiratory-based control protocol of FIG. 6 to present patientrespiratory data, illustrating a patient respiration level within asecond range.

FIG. 10C is one embodiment of a visual output that may be used by therespiratory-based control protocol of FIG. 6 to present patientrespiratory data, illustrating a patient respiration level within athird range.

DETAILED DESCRIPTION

FIG. 1 presents a schematic of one embodiment of what may becharacterized as a medical navigation/visualization system and/or ananatomical modeling system 5. The medical navigation/visualizationsystem 5 will be briefly addressed herein, as it is one such system thatmay utilize the respiratory-based control functionality that will beaddressed in detail below. The medical navigation/visualization system 5is also discussed in detail in U.S. Pat. No. 7,263,397, that is entitled“METHOD AND APPARATUS FOR CATHETER NAVIGATION AND LOCATION AND MAPPINGIN THE HEART,” that issued on Aug. 28, 2007 and is assigned to theassignee of this patent application, and the entire disclosure of whichis incorporated by reference in its entirety herein.

The patient 11 is only schematically depicted as an oval for clarity. Ina preferred embodiment, three sets of surface or patch electrodes areshown as 18, 19 along a Y-axis; as 12, 14 along an X-axis; and 16, 22along a Z-axis. Patch electrode 16 is shown on the surface closest tothe observer, and patch electrode 22 is shown in outline form to showits placement on the back of patient 11. An additional patch electrode,which may be referred to as a “belly” patch, is also seen in the figureas patch electrode 21. Each patch electrode 18, 19, 12, 14, 16, 22, 21is independently connected to a multiplex switch 24. The heart 10 ofpatient 11 lies between these various sets of patch electrodes 18, 19,12, 14, 16, 22. Also seen in this figure is a representative catheter 13having a single distal electrode 17 for clarity. This distal electrode17 may be referred to as the “roving electrode” or “measurementelectrode” herein. Multiple electrodes on each catheter may be used. Afixed reference electrode 31 attached to a heart wall is also seen inthe figure on an independent catheter 29. For calibration purposes, thiselectrode 31 is known to be stationary on the heart. It should beappreciated that in use the patient 11 will have most or all of theconventional 12 lead ECG system in place as well, and this ECGinformation is available to the system although not illustrated in thefigure.

Each patch electrode 18, 19, 12, 14, 16, 22, 21 is coupled to the switch24, and pairs of electrodes 18, 19, 12, 14, 16, 22 are selected bysoftware running on computer system 20, which couples these electrodes18, 19, 12, 14, 16, 22 to the signal generator 25. A pair of electrodes,for example electrodes 18 and 19, may be excited by the signal generator25 and they generate a field in the body of the patient 11 and the heart10. During the delivery of the current pulse, the remaining patchelectrodes 12, 14, 16, 22 are referenced to the belly patch electrode21, and the voltages impressed on these remaining electrodes 12, 14, 16,22 are measured by the analog-to-digital or A-to-D converter 26.Suitable lowpass filtering of the digital data may be subsequentlyperformed in software to remove electronic noise and cardiac motionartifact after suitable low pass filtering in filter 27. In thisfashion, the various patch electrodes 18, 19, 12, 14, 16, 22 are dividedinto driven and non-driven electrode sets. While a pair of electrodesare driven by the signal generator 25, the remaining non-drivenelectrodes are used as references to synthesize the orthogonal driveaxes.

The belly patch electrode 21 is seen in the figure is one alternative toa fixed intra-cardiac electrode 31. In many instances, a coronary sinuselectrode or other fixed electrode in the heart 10 can be used as areference for measuring voltages and displacements. The raw patchvoltage data is measured by the A-to-D converter 26 and stored in thecomputer system 20 under the direction of software. This electrodeexcitation process occurs rapidly and sequentially as alternate sets ofpatch electrodes 18, 19, 12, 14, 16, 22 are selected, and the remainingmembers of the set are used to measure voltages. This collection ofvoltage measurements may be referred to herein as the “patch data set”.The software has access to each individual voltage measurement made ateach individual patch electrode 18, 19, 12, 14, 16, 22 during eachexcitation of each pair of electrodes 18, 19, 12, 14, 16, 22. The rawpatch data is used to determine the “raw” location in three spaces (X,Y, Z) of the electrodes inside the heart 10, such as the rovingelectrode 17.

If the roving electrode 17 is swept around in the heart chamber whilethe heart 10 is beating, a large number of electrode locations arecollected. These data points are taken at all stages of the heartbeatand without regard to the cardiac phase. Since the heart 10 changesshape during contraction, only a small number of the points representthe maximum heart volume. By selecting the most exterior points, it ispossible to create a “shell” representing the shape of the heart 10,e.g., at its maximum heart volume. The location attribute of theelectrodes within the heart 10 are measured while the electric field isimpressed on the heart 10 by the surface patch electrodes 18, 19, 12,14, 16, 22.

FIG. 2 shows a catheter 13, which may be a conventional EP catheter inthe heart 10. In the figure, the catheter 13 is shown in the leftventricle 50. The catheter 13 has additional electrodes 52, 54, and 56.Since these electrodes 52, 54, 56 lie in the heart 10, the locationprocess detects their location in the heart 10. While they lie on thesurface and when the signal generator 25 is “off”, each electrode 18,19, 12, 14, 16, 22 can be used to measure the voltage on the heartsurface. The magnitude of this voltage, as well as the timingrelationship of the signal with respect to the heartbeat events, may bemeasured and presented to the cardiologist through the display 23. Thepeak-to-peak voltage measured at a particular location on the heart wallis capable of showing areas of diminished conductivity, and which mayreflect an infarcted region of the heart 10. The timing relationshipdata are typically displayed as “isochrones”. In essence, regions thatreceive the depolarization waveform at the same time are shown in thesame false color or gray scale.

FIG. 3 shows an illustrative computer display from the computer system20 (FIG. 1). The display 23 (FIG. 1) is used to show data to thephysician user and to present certain options that allow the user totailor the system configuration for a particular use. It should be notedthat the contents on the display 23 can be easily modified and thespecific data presented is only of a representative nature. An imagepanel 60 shows a geometry of the heart chamber 62 which shows“isochrones” in false color, which is shown in grayscale in the figurewith guide bar 64. In this image, the improved location methodology hasbeen used with a roving catheter to create a chamber representation thatis displayed as a smoothed contoured image.

The guide bar 64 is graduated in milliseconds and it shows theassignment of time relationship for the false color image in thegeometry. The relationship between the false color on the geometry image62 and the guide bar 64 is defined by interaction with the user in panel66 as best seen in FIG. 4.

FIG. 4 is an enlargement of panel 66 of FIG. 3. The panel 66 representsthe timing information used to generate the isochrones seen on geometry62. In general, a fiducial point is selected as the “zero” time. In thefigure, the inflection point 70 of a voltage appearing on a referenceelectrode is used as the primary timing point for the creation ofisochrones. This voltage may be acquired from either a virtual referenceor a physical reference such as electrode 31 seen in FIG. 1. Thisvoltage tracing in the figure is labeled “REF” on FIG. 4. The rovingelectrode signal is seen on FIG. 4 and it is labeled “ROV” in thefigure. The inflection point of this voltage signal is shown at 72. Thecolor guide bar 65 shows the assignment of color or grayscale tone forthe timing relationship seen between inflections 70 and 72.

Also shown on panel 66 of FIG. 4, is the amplitude of the signal presenton the roving electrode 17. Note that it lies between two adjustablebands 74 and 76. These bands 74, 76 are used to set selection criteriafor the peak-to-peak voltage of the signal. In practice, regions of theheart 10 with low peak-to-peak voltage are the result of infarctedtissue, and the ability to convert voltage to grayscale or false colorallows identification of the regions that are infarcted or ischemic.

For completeness, in description the tracing 78 labeled “V1” in FIG. 4is a reference electrode on the surface of the patient 11 in theconventional 12 lead ECG setup. This reference orients the physician tothe same events detected on the surface of the patient 11.

Based upon the foregoing, the basic software process proceeds stepwiseby first selecting a set of electrodes and then driving them withcurrent pulses. While the current pulses are being delivered, thevoltages on several of the other remaining surface electrodes andintracavitary electrodes are measured and stored.

It is this process that collects the various data points associated withmultiple endocardial electrode locations. Each point in this set hascoordinates in space. In general, several dozen points are collected. Alarger data set results in a more complex and higher resolutionrepresentation of the heart 10; however, it is computationally moreexpensive. This raw location data may be corrected for respiration andother artifacts, and then a geometry process is started. In thisprocess, the exterior-most location points in the data are used tocreate a shape. The surface may be in the form of a convex hull usingstandard algorithms such as Qhull. This surface is then resampled over amore uniform grid and interpolated to give a reasonably smooth surfacestored as a “geometry” for presentation to the physician. Any of thealgorithms known in the art may be used to compute the convex hullshape. This hull shape estimates the boundary of the interior of theheart 10 from the set of points. The process can then proceed toresample the convex hull on a regular grid of points in physical space.By resampling the computed hull shape on the regular gird, a larger setof points in generated. Most significantly, this enlarged set of pointsensures that computational points are available along the length of eachedge of the hull. The next process uses an algorithm for smoothing theconvex hull shape. This process forms a mathematically differentiableshape approximating the physiologic shape of the heart chamber. Any of anumber of interpolation processes can be adopted to implement thisportion of the process. The final process causes the model to exit to adisplay routine or other process where the computed shape is used forfurther analysis. This geometry surface is also used as a displaysurface to present the activation maps. This is also the surface thatthe EP data is projected on.

As described, the EP catheters are moved over the surface of the heart10 and while in motion they detect the electrical activation of theheart 10 or EP signals on the surface of the heart 10. During eachmeasurement, the real time location of the catheter electrode is noted,along with the value of the EP voltage or signal. Since this data is nottaken with the location data used to create the geometry, a projectionprocess is used to place the electrical information on the nearest heartsurfaces represented by the geometry. One implementation is to selecttwo close points or locations in the EP data set and to “drop” a pointperpendicular to the “nearest” surface point on the geometric surface.This new point is used as the “location” for the presentation of EP datain the images presented to the physician.

The above-noted surface or patch electrodes 12, 14, 16, 22, 18, 19 usedby navigation/visualization system 5 of FIG. 1 may also be used toprovide patient respiration data for respiratory-based control of amedical procedure using a transthoracic impedance (e.g., by using alow-level signature frequency, which is sent and received betweenvarious of the patch electrodes 12, 14, 16, 22, 18, 19). Generally, anappropriate signal may be sent to a particular one of the patchelectrodes 12, 14, 16, 22, 18, 19, and a signal corresponding with theoutput of one or more of the other patch electrodes 12, 14, 16, 22, 18,19 may be provided for assessment in relation to what may becharacterized as a first condition, where patient respiration data(e.g., a respiration level) exceeds one or more patient respirationthresholds. Identification of the first condition may then be used tosuspend at least one medical procedure.

Impedance is one parameter that is reflective of the patient'srespiration and that may be used for the above-noted first conditionassessment. Other examples, depending on the mapping system or equipmentused, could include magnetics, coupling distance, and motion. Theimpedance changes during a patient's respiratory cycle are based uponthe patient's respiratory level. For instance, the amount of air in thepatient's lungs has an effect on the impedance. The resistively of thepatient's blood also changes during the patient's respiratory cycle andthereby has an effect on the impedance. Impedance data regarding thepatient's respiration may be acquired/determined in any appropriatemanner, for instance via the output from one or more of the above-notedpatch electrodes 12, 14, 16, 22, 18, 19. As the amount of air in thelungs changes, the measured impedance between the electrodes willchange. This change is recorded as impedance data. This impedance datamay be assessed to identify the respiratory stage, or correlate with arespiratory stage, and be analyzed. This analysis will identify anyoccurrence of a first condition, and is used to then responsivelysuspend at least one medical procedure.

One embodiment of a medical system that utilizes respiratory-basedcontrol is schematically presented in FIG. 5 and is identified byreference numeral 100. The medical system 100 generally includes arespiration assessment system 112 and medical procedure logic 118.Generally, the respiration assessment system 112 may be incorporatedand/or utilized by any appropriate medical system, such as an anatomicalmodeling system of any appropriate type (e.g., electrical-based;magnetics-based). The medical procedure logic 118 may provide anyfunctionality or combination of functionalities (e.g. to control atleast one medical procedure in at least some respect), and furthermoremay be associated with any component or combination of components, suchas the navigation/visualization system 5 of FIG. 1 or any anatomicalmodeling system of any appropriate type. For instance, the respirationassessment system 112 may be used to suspend the acquisition and/orstorage of location information on an anatomical/physiologicalsurface/structure.

The respiration assessment system 112 includes respiration assessmentlogic 116 that is operatively interconnected with the medical procedurelogic 118, and may be characterized as further including at least onesensor 108 that is associated with a patient 104, along with a display184. Each sensor 108 and the display 184 may also be part of and/or usedby one or more other parts of the medical system 100, such as thenavigation/visualization system 5 of FIG. 1.

Each sensor 108 used by the medical system 100 of FIG. 5 may be of anyappropriate size, shape, configuration and/or type, and furthermore maybe positioned at any appropriate location on or relative to the patient104. For instance, one or more of the sensors 108 may be in the form ofthe surface or patch electrodes 12, 14, 16, 22, 18, 19 used by thenavigation/visualization system 5 of FIG. 1, and which would beappropriately attached at an appropriate location on the skin of thepatient 104 (e.g., in the above-noted arrangement). The output from oneor more of these sensors 108 may be utilized by the respirationassessment system 112 to provide respiratory-based control of at leastone medical procedure. That is, data provided by one or more of thesesensors 108 should be in the form of patient respiratory data or datathat is reflective of the patient's respiratory cycle (e.g., data thatreflects the changes in the patient's respiratory level during therespiratory cycle).

Data provided by one or more of these sensors 108 is used by therespiration assessment system 112 to provide a respiratory-based controlof one or more medical procedures, for instance by communication betweenthe respiration assessment logic 116 and the medical procedure logic118. This respiration assessment logic 116, along with the medicalprocedure logic 118 for that matter, may be incorporated/implemented inany appropriate manner, such as in software, hardware, or anycombination thereof, and may be disposed at any appropriate location(e.g., the respiration assessment logic 116 and medical procedure logic118 need not be co-located, although such may be the case).

One embodiment of a respiratory-based control protocol that may beutilized by the respiration assessment logic 116 (FIG. 5) is illustratedin FIG. 6 and is identified by reference numeral 120. Step 124 of therespiratory-based control protocol 120 is directed to executing amedical procedure, such as through the medical procedure logic 118 (FIG.5). This medical procedure may be of any appropriate type, may beundertaken by any appropriate component or combination of components(e.g., using one or more endocardial electrodes, such as a catheterelectrode or the like), and may be undertaken on any basis (e.g., themedical procedure may be performed continuously over a certain period oftime; the medical procedure may be performed at one or more times over acertain period of time). In the context of the navigation/visualizationsystem 5 of FIG. 1, the medical procedure associated with step 124 ofthe respiratory-based control protocol 120 of FIG. 6 may becharacterized as marking a physiological location on or within the bodyof the patient 104 (FIG. 5), such as a discrete location within theheart of the patient 104, acquiring and/or storing physiologicallocation information, or the like. Representative medical procedures forstep 124 of the respiratory-based control protocol 120 of FIG. 6 includewithout limitation cardiac labeling, cardiac geometry collection,cardiac mapping, cardiac lesion marking, and the like.

Patient respiration data is acquired through execution of step 128 ofthe respiratory-based control protocol 120. Patient respiration data maybe acquired on any timing basis (e.g., on a real-time basis; inaccordance with any algorithm), but is preferably acquired throughoutthe medical procedure associated with step 124. It also may be desirableto acquire a patient respiration data sample before the medicalprocedure associated with step 124 is initiated and as will be discussedin more detail below in relation to the initialization protocol 148 ofFIG. 7. Any data that is representative of the patient's respiration(e.g., respiration level) may be acquired through execution of step 128of the protocol 120, so long as this data may be assessed to determineif a first condition exists. Impedance data is one such parameter asnoted above. Impedance may be more generally characterized aselectrophysiological data. Other electrophysiological data/parametersmay be appropriate for providing a first condition assessment. Otherparameters on which a first condition assessment could be based includewithout limitation pressure data from one or more pressure-sensingcatheters or other appropriate pressure sensors, one or more outputsfrom respiration equipment, and magnetic data, e.g., magnetic locationdata.

The patient respiration data acquired through step 128 of therespiratory-based protocol 120 may be displayed through execution ofstep 136 of the protocol 120, but in any case is evaluated throughexecution of step 132 of the protocol 120. This evaluation may beundertaken in any appropriate manner. Preferably, all patientrespiration data is evaluated through step 132, although such may not berequired in all instances, and preferably this evaluation occurs on areal-time basis or at least with some reasonable degree of frequency.The patient respiration data evaluation associated with step 132 may becharacterized as determining if the patient's respiration exceeds one ormore respiration thresholds, if the patient's respiration is outside ofa predetermined respiration range (e.g., having a pair of limits orthresholds), or if the patient's respiration exceeds a baselinerespiration value by more than a certain, predetermined amount (e.g., ona percentage basis or an absolute basis). Such an occurrence may becharacterized as a “sudden” respiratory event (e.g., gasping, sighing,talking, coughing, and snoring). A sudden respiratory event mayadversely affect the medial procedure associated with step 124 in atleast some manner. Accordingly it is desirable to identify these“sudden” respiratory events and adjust the procedure accordingly.

The respiratory-based control protocol 120 generalizes the above-notedsudden respiratory event as one type of a “first condition” in its step140. If a first condition exists, the medical procedure of step 124 maybe suspended in any appropriate manner via step 144 of the protocol 120.Patient respiration data continues to be acquired and evaluated throughsteps 128 and 132 during any suspension of the medical procedure, butnow for purposes of determining if the first condition no longer exists.Once the first condition no longer exists, the medical procedure may bere-initiated in any appropriate manner, such as through anotherexecution of step 124 of the protocol 120. The medical procedure couldbe resumed on any appropriate basis (e.g., a certain amount of timeafter a first condition has been identified).

Various additional features may be utilized by the respiratory-basedcontrol protocol 120 of FIG. 6, such as the initialization protocol 148of FIG. 7, the respiration evaluation protocol 164 of FIG. 8, and therespiration evaluation protocol 188 of FIG. 9. Each of these protocolswill now be addressed.

The respiratory-based control protocol 120 of FIG. 6 evaluates patientrespiration data to identify any occurrence of a first condition forpurposes of suspending at least one medical procedure during theexistence of this first condition. One way in which patient respirationdata may be evaluated for this purpose is to compare the same to one ormore respiration thresholds. The initialization protocol 148 of FIG. 7may be utilized to identify one or more respiration thresholds that areappropriate for the patient 104 (FIG. 5). In this regard, an appropriatepatient respiration data sample is acquired through execution of step152 of the initialization protocol 148. Preferably this patientrespiration data sample includes at least one complete respiratory cycle(at least one inhalation and one exhalation) and does not include any ofthe above-noted type of “sudden” respiratory events. In one embodiment,patient respiratory data is acquired for at least about 10 or 12 secondsto provide such a data sample. Although a respiration threshold may beestablished in any appropriate manner through a review/analysis of thispatient respiration data sample, in one embodiment the maximum andminimum amplitudes of a waveform of the patient respiration data may becalculated or otherwise determined (e.g., respiration baselines), andthereafter may be used to define a maximum respiration threshold (e.g.,+100% in FIGS. 10A-C to be discussed below) and a minimum respirationthreshold (e.g., −100% in FIGS. 10A-C to be discussed below). Therefore,the current patient respiration data may be visually presented as apercentage in relation to maximum and minimum respiration thresholdvalues and as will be addressed below in relation to the respirationevaluation protocol 188 of FIG. 9 and where representative displayoutputs are presented in FIGS. 10A-C.

Once an appropriate patient respiration data sample has been obtainedthrough execution of step 152 of the initialization protocol 148, therespiration evaluation protocol 120 of FIG. 6 may be executed in anyappropriate manner (e.g., through execution of step 156 of theinitialization protocol 148 of FIG. 7). There may be a desire/need toreestablish one or more of the respiration thresholds for purposes ofthe respiratory-based control protocol 120. In this regard, step 160 ofthe initialization protocol 148 indicates that the respiratory-basedcontrol protocol 120 may be suspended for a repetition of step 152 ofthe initialization protocol 148 and its acquisition of another patientrespiration data sample. Since it may not be required to acquire two ormore patient respiration data samples for purposes of therespiratory-based control protocol 120, step 160 of the initializationprotocol 140 may be of an optional nature and as indicated by the dashedlines in FIG. 7.

Patient respiration data may be evaluated in any appropriate manner forpurposes of the respiratory-based control protocol 120 of FIG. 6. Oneembodiment of a respiration evaluation protocol that may be utilized bythe protocol 120 of FIG. 6 to execute the patient respiration dataevaluation is illustrated in FIG. 8 and is identified by referencenumeral 164. Step 168 of the protocol 164 of FIG. 8 may replace step 132of the protocol 120 of FIG. 6, while step 172 of the protocol 164 ofFIG. 8 may replace step 140 of the protocol 120 of FIG. 6. Step 168 ofthe respiration evaluation protocol 164 of FIG. 8 provides a comparisonof the patient respiration data with at least one respiration threshold.This comparison may be provided in any appropriate manner (e.g., usingan appropriate comparator). If the patient respiration data currentlybeing evaluated in accordance with step 168 of the respirationevaluation protocol 164 does not exceed any respiration threshold beingutilized and which is determined through step 172, the respirationevaluation protocol 164 allows for a continuance of the medicalprocedure (e.g., through step 176). Otherwise, the respirationevaluation protocol 164 proceeds to step 180 and which results in orotherwise accommodates a suspension of the medical procedure throughexecution of step 180. This suspension of the medical procedure may beinitiated in any appropriate manner (e.g., automatically, manually). Inaccordance with the respiratory-based protocol 120 of FIG. 6, once eachrespiration threshold(s) is no longer being exceeded, the medicalprocedure may be reinitiated. However, the medical procedure couldresume on any appropriate basis, such as after the expiration of apredetermined amount of time from the identification of a firstcondition.

Another embodiment of a respiration evaluation protocol that may beutilized by the protocol 120 of FIG. 6 to execute the patientrespiration data evaluation associated with its steps 132 and 140 isillustrated in FIG. 9 and is identified by reference numeral 188. Therespiratory-based control protocol 120 of FIG. 6 provides for thedisplay of patient respiration data through its step 136, as previouslynoted. The respiration evaluation protocol 188 of FIG. 9 includes thisdisplay functionality in relation to its patient respiration dataassessment (and which thereby may replace the display step 136 of theprotocol 120 of FIG. 6).

The respiration evaluation protocol 188 of FIG. 9 accommodatescategorizing patient respiration data through its evaluation, and whichmay be used determine the manner in which patient respiration data isdisplayed. In this regard, the protocol 188 determines if the patientrespiration data that is currently being evaluated is within one ofthree ranges, and this determination may be made in any order (e.g., thefirst determination may be whether the patient respiration data iswithin the third range, versus the first range). Any appropriate numberof ranges may be utilized by the protocol 188 (e.g., two or more). Eachsuch respiration range may encompass any appropriate range ofrespiration values. Generally and for purposes of the display functionof the respiration evaluation protocol 188 of FIG. 9, each respirationrange is displayed in a different color to visually present at least oneindication of the patient's current respiration level.

Step 192 of the protocol 188 determines if the patient respiration datais within a first range. In one embodiment and as will be discussedbelow in relation to FIGS. 10A-C, the first range corresponds withpatient respiration data that is within 0% to ±75% of the correspondingrespiration threshold, and which may be equated with a “normal”respiration. If the patient respiration data currently being evaluatedis within the first range, the protocol 188 proceeds to step 196 andwhich results in the current patient respiration data being displayed ina first color (e.g., green), as well as for a continuance of the medicalprocedure through step 218.

Step 200 of the protocol 188 determines if the patient respiration datais within a second range. In one embodiment, the second rangecorresponds with patient respiration data that is between ±75% and ±100%of the corresponding respiration threshold, and which may be equatedwith a “cautionary” respiration zone that is between a “normal”respiration zone and respiration levels that have been associated with asudden respiratory event or a first condition. If the patientrespiration data currently being evaluated is within the second range,the protocol 188 proceeds from step 200 to step 204 and which results inthe current patient respiration data being displayed in a second color(e.g., yellow), as well as for a continuance of the medical procedurethrough step 218.

Patient respiration data that falls outside of each of the first andsecond ranges is equated with a sudden respiratory event (e.g., at least±100% of the corresponding respiration threshold, and which equates witha first condition) for purposes of the respiration evaluation protocol188 and as indicated by step 208. The protocol 188 proceeds to step 212in this case and results in the current patient respiration data beingdisplayed in a third color (e.g., red). Other appropriate indications ofthis first condition may be presented as well (e.g., the entirerespiration meter 220 of FIGS. 10A-C may flash). Moreover and as notedabove, the medical procedure may be suspended in this instance in anyappropriate manner, for instance through execution of step 216 of theprotocol 188. In accordance with the respiratory-based protocol 120 ofFIG. 6, once the patient respiration data is no longer within the thirdrange, the medical procedure may be re-initiated or otherwise asdiscussed herein.

FIGS. 10A-C present representative displays that accommodate use of therespiration evaluation protocol 188 of FIG. 9. The displays of FIGS.10A-C are each in the form of a respiration meter 220 that includesgradations 228, a datum 224 that occupies the “0” position on the meter220 (although this does not mean that the associated respiration valueis in fact “0” at this time), and a movable indicator bar 232. Theindicator bar 232 moves during a patient's respiratory cycle and to amagnitude that corresponds with the patient's current respiration level.That is, the indicator bar 232 rises and falls on the respiration meter220 in accordance with the changing of patient's respiration levelduring the respiration cycle.

The respiration meter 220 expresses the patient's respiration as apercentage of two respiration thresholds—what may be characterized as amaximum respiration threshold and a minimum respiration threshold, andeach of which may be of any appropriate value and determined on anyappropriate basis. For instance, a maximum respiration value or anaverage maximum respiration value may be determined from a patientrespiratory data sample, and which may be used to define or establishone respiration baseline. A corresponding respiration threshold may thenbe set or established from this respiration baseline and which may be ofany appropriate value. Although the maximum respiration threshold couldbe set equal to the maximum respiration baseline, in one embodiment themaximum respiration threshold is greater/less than the maximumrespiration baseline by a certain amount. Similarly a minimumrespiration value or an average minimum respiration value may bedetermined from a patient respiratory sample, and which may be used todefine or establish another respiratory baseline. A correspondingrespiration threshold may then be set or established from thisrespiration baseline and which may be of any appropriate value. Althoughthe minimum respiration threshold could be set equal to the minimumrespiration baseline, in one embodiment the minimum respirationthreshold is greater/less than the minimum respiration baseline by acertain amount.

The maximum respiration threshold (+100% in the illustrated embodiment)may correspond with the end of patient inhalation, while the minimumrespiration threshold (−100% in the illustrated embodiment) maycorrespond with the end of a patient exhalation, although the reversecould be utilized as well. Both the maximum respiration threshold andthe minimum respiration threshold are referenced to a common datum 224.Although this datum is illustrated as having a value of 0%, this doesnot necessarily mean that the value of the patient respiration datacorresponding with the datum 224 is in fact “0,” although such could bethe case. For instance, the datum 224 could be any appropriate value. Inone embodiment, patient respiration data on the “plus” side of therespiration meter 220 corresponds with respiration levels on one side ofa reference line associated with a waveform embodying patientrespiration data, while patient respiration data on the “minus” side ofthe respiration meter 220 correspond with respiration levels on theopposite side of this same reference line.

Although the absolute value of the maximum respiration threshold valuecould be the same as the absolute value of the minimum respirationthreshold value, such need not be the case. Stated another way, thedifferential value between the datum 224 and each of the maximum andminimum respiration thresholds may or may not be the same. In any case,when current patient respiration data is being evaluated by therespiration evaluation protocol 188 of FIG. 9 and when using therespiration meter 220 of FIGS. 10A-C, the value of the current patientrespiration data could be divided by the value associated with therelevant one of the maximum respiration threshold and the minimumrespiration threshold. If the values of the maximum and minimumthresholds were the same, obviously only one value would need to beutilized. The respiration threshold that should be used as thedenominator in relation to the current respiration data evaluation couldbe determined on any appropriate basis. For instance, the maximumrespiration threshold could be used if the value of the current patientrespiration data was within a certain range, while the minimumrespiration threshold could be used if the value of the current patientdata was within another range. Another option would be to use themaximum respiration threshold if the patent respiration data was on oneside of a reference line associated with a waveform embodying thepatient respiration data, and to use the minimum respiration thresholdif the patient respiration data was on the opposite side of this samereference line (e.g., if the patient respiration data was beingpresented by a waveform for the first condition analysis).

FIG. 10A is a representative position of the indicator bar 232 withinthe first range and in accordance with the above-noted embodiment.Therefore, the indicator bar 232 would be presented in a first color.FIG. 10B is a representative position of the indicator bar 232 withinthe second range and in accordance with the above-noted embodiment.Therefore, the indicator bar 232 would be presented in a second color.Finally, FIG. 10C is a representative position of the indicator bar 232within the third range and in accordance with the above-notedembodiment. Therefore, the indicator bar 232 would be presented in athird color. In addition to or in alternative to a color, otherindicators may be used, such as shape or sound.

The respiration assessment system 112 may be used for any appropriateapplication. For instance, it may be desirable to incorporate therespiration assessment system 112 into the navigation/visualizationsystem 5 of FIG. 1 and as previously noted. The same display thatpresents navigation/visualization data could provide patient respiratoryassessment data, or this data could be presented in side-by-siderelation to each other on separated displays, or at least on displaysthat are proximate to each other. The respiration assessment system 112could be used with a navigation/visualization system that does notinclude any respiration compensation functionality, as well as with anavigation/visualization system that does incorporate appropriaterespiration compensation functionality.

Respiration compensation functionality is available in the Ensite™Advanced Mapping System by St. Jude Medical, Inc., and is addressed bythe above-noted U.S. Pat. No. 7,263,397, which is hereby incorporated byreference. Generally, respiration compensation functionality attempts tominimize the respiration artifact from cardiac models and mapping. Thatis, during patient respiration the heart and any electrodes positionedtherein will move relative to the various patch electrodes that arepositioned on the patient's skin at any appropriate location. Thesurface electrode impedance is monitored in relation to a respiratorydata sample that is taken of at least one patient respiration cycle thatdoes not include any sudden respiratory event. As the impedance changesat the surface electrodes, the respiration compensation functionalityadapts the impedance output based upon the initial respiratory datasample to adaptively compensate for motion artifacts.

The above-noted type of respiration compensation functionality therebyshows the heart and any endocardial electrode without any (or with onlyminimal) respiratory motion. The respiration assessment system 112 couldbe used in this type of system configuration. In this regard, it may bedesirable to present those gradations 228 in the respirationcompensation zone in a different color than the remaining gradations228, although this is optional. The respiration assessment system 112could also be used without any respiration compensation functionality atall, where the navigation/visualization system would then display theheart and any endocardial electrodes with respiratory motion. Therespiration assessment system 112 may also be used other than withnavigation/visualization systems.

Although embodiments of this invention have been described above with acertain degree of particularity, those skilled in the art could makenumerous alterations to the disclosed embodiments without departing fromthe spirit or scope of this invention. All directional references (e.g.,upper, lower, upward, downward, left, right, leftward, rightward, top,bottom, above, below, vertical, horizontal, clockwise, andcounterclockwise) are only used for identification purposes to aid thereader's understanding of the present invention, and do not createlimitations, particularly as to the position, orientation, or use of theinvention. Joinder references (e.g., attached, coupled, connected, andthe like) are to be construed broadly and may include intermediatemembers between a connection of elements and relative movement betweenelements. As such, joinder references do not necessarily infer that twoelements are directly connected and in fixed relation to each other. Itis intended that all matter contained in the above description or shownin the accompanying drawings shall be interpreted as illustrative onlyand not limiting. Changes in detail or structure may be made withoutdeparting from the spirit of the invention as defined in the appendedclaims.

1. (canceled)
 2. A respiratory assessment system for use in connectionwith a cardiac navigation and/or visualization system, the respiratoryassessment system comprising: a respiration assessment logic configuredto: receive current patient respiration data from the cardiac navigationand/or visualization system as input; evaluate the current patientrespiration data to identify whether a sudden respiratory event exists;and send a medical procedure suspension command to the cardiacnavigation and/or visualization system upon identifying that the suddenrespiratory event exists.
 3. The respiratory assessment system accordingto claim 2, wherein the current patient respiration data from thecardiac navigation and/or visualization system compriseselectrophysiological data.
 4. The respiratory assessment systemaccording to claim 3, wherein the electrophysiological data comprisesimpedance data.
 5. The respiratory assessment system according to claim4, wherein the respiration assessment logic is configured to evaluate anamplitude of the impedance data to identify whether the suddenrespiratory event exists.
 6. The respiratory assessment system accordingto claim 2, wherein the sudden respiratory event is representative of acurrent patient respiration that is outside of a preset respirationrange.
 7. The respiratory assessment system according to claim 6,wherein the preset respiration range is adjustable.
 8. The respiratoryassessment system according to claim 2, wherein the sudden respiratoryevent is representative of a current patient respiration that exceeds atleast one respiration threshold.
 9. A respiratory assessment and controlmodule for use in performing a cardiac medical procedure, therespiratory assessment and control module comprising: a respirationassessment logic configured to: receive electrophysiological data fromat least one sensor; evaluate the electrophysiological data to determinea current respiratory condition of a patient; and upon determining thatthe current respiratory condition of the patient comprises a suddenrespiratory event, send a medical procedure suspension command to amedical device.
 10. The respiratory assessment and control moduleaccording to claim 9, wherein the electrophysiological data comprisesimpedance data.
 11. The respiratory assessment and control moduleaccording to claim 10, wherein the respiration assessment logic isconfigured to evaluate an amplitude of the impedance data to determinethe current respiratory condition of the patient.
 12. The respiratoryassessment and control module according to claim 9, wherein the suddenrespiratory event is representative of a current respiratory conditionof the patient that is outside of a preset respiration range.
 13. Therespiratory assessment and control module according to claim 12, whereinthe preset respiration range is adjustable.
 14. The respiratoryassessment and control module according to claim 9, wherein the suddenrespiratory event is representative of a current respiratory conditionof the patient that exceeds at least one respiration threshold.
 15. Arespiratory assessment system for use in connection with a cardiacnavigation and/or visualization system configured for generating a mapcontaining electrophysiology data, the respiratory assessment systemcomprising: a respiration assessment logic configured to: receivecurrent patient respiration data as input; compare the current patientrespiration data to at least one respiration threshold to identifywhether a sudden respiratory event exists; and send a medical proceduresuspension command to the cardiac navigation and/or visualization systemupon identifying that the sudden respiratory event exists, the medicalprocedure suspension command configured to suspend the population ofelectrophysiology data to the map during a period of time of the suddenrespiratory event.
 16. The respiratory assessment system according toclaim 15, wherein the electrophysiological data comprises impedancedata.
 17. The respiratory assessment and control module according toclaim 15, wherein the sudden respiratory event is representative of acurrent respiratory condition of the patient that is outside of a presetrespiration range.
 18. The respiratory assessment and control moduleaccording to claim 17, wherein the preset respiration range isadjustable.
 19. The respiratory system of claim 15, wherein the at leastone respiration threshold comprises a peak-to-peak range associated witha first condition.
 20. The respiratory system of claim 19, wherein theat least one respiration threshold further comprises a secondpeak-to-peak range associated with a second condition different than thefirst condition.
 21. The respiratory system of claim 15, wherein the atleast one respiration threshold comprises a maximum respirationthreshold corresponding to patient inhalation and a minimum respirationthreshold corresponding to patient exhalation.